1. Technical Field
The present invention relates to a vibrating reed, and particularly, to a vibrating reed with reduced vibration leakage, and an electronic device and an electronic apparatus both using the vibrating reed.
2. Related Art
Heretofore, as an angular velocity sensor for detecting a rotational angular velocity of a rotating system, a vibration-type gyro sensor using a piezoelectric vibrating reed or a vibrator having a piezoelectric vibrating reed accommodated in a container has been used. The vibration-type gyro sensor is used for a car navigation system, camera shake detection of a still camera, and the like.
For the piezoelectric vibrating reed used for the vibration-type piezoelectric gyro sensor, a piezoelectric vibrating reed configured of a plurality of vibrating arms extended in the same plane and a base portion coupling the vibrating arms together is used. The vibration-type piezoelectric gyro sensor drives and vibrates the piezoelectric vibrating reed with a drive circuit, detects a detection vibration generated according to a rotational angular velocity with a detection circuit, and outputs an electric signal. A driving vibration is generated in the whole or a portion of the plurality of vibrating arms. When a rotational angular velocity is applied to the piezoelectric vibrating reed, a Coriolis force in a direction orthogonal to a driving vibration direction acts on the vibrating arm that is driven and vibrated, and a detection vibration according to the rotational angular velocity is generated in the whole or a portion of the plurality of vibrating arms.
When axes perpendicular to each other are defined as an X-axis and a Y-axis, a related-art piezoelectric vibrating reed has a pair of coupling arms extended from a base portion in opposite directions along the X-axis, a pair of detection arms extended from the base portion in opposite directions along the Y-axis, and a pair of vibrating arms extended from each of the coupling arms in opposite directions along the Y-axis. The piezoelectric vibrating reed adopts a structure in which the base portion and a support portion are coupled with a coupling portion (refer to JP-A-2010-256332).
In the piezoelectric vibrating reed, since the vibrating arm vibrates when the piezoelectric vibrating reed is driven, the vibration sometimes leaks to the support portion via the coupling portion. Therefore, in JP-A-2010-256332, the coupling portion is made into an S-shape, so that a path on the coupling portion from the base portion to the support portion is bent and lengthened. Due to this, the amount of damping of vibration generated in the vibrating arm and leaking in the coupling portion via the base portion is increased in the coupling portion, so that the amount of vibration leaking to the support portion is reduced.
However, due to a reduction in the size of the piezoelectric vibrating reed, the size of the coupling portion is also reduced, and therefore, the path on the coupling portion from the base portion to the support portion is shortened. Therefore, the amount of damping of vibration in the coupling portion is reduced, so that the amount of vibration leaking to the support portion is increased. Due to this, the excitation efficiency of the vibrating arm or a temperature characteristic of a resonant frequency is deteriorated.